Self-attaching female fastener elements, including pierce and clinch nuts formed by cold heading techniques, are well known in the art. A pierce nut pierces an opening in a panel during installation and a pilot portion of the pierce nut is received through the pierced panel opening during attachment. A clinch nut is attached to a panel having a preformed or prepierced opening. As used herein, the term self-attaching female fastener element is intended to be generic to pierce and clinch female fastener elements, including pierce and clinch nuts. Such self-attaching female fastener elements are, however, asymmetrical and must therefore be oriented in an installation head prior to installation in a panel.
Pierce and clinch nuts manufactured by the assignee of this application are conventionally installed in mass production applications and used by the automotive and appliance industries to interconnect components of an assembly. In a typical application, an installation head having a reciprocating plunger is installed in one platen of a die press, typically the upper die platen, and a die member or die button is installed in the opposite die platen, typically the lower die platen. The self-attaching female fastener elements are then fed through a chute from a hopper to the installation head and a self-attaching fastener is installed in a panel with each stroke of the die press. However, because the self-attaching female fastener elements are asymmetrical, the female fastener elements must be oriented prior to receipt in the feed chute, typically in the hopper. As will be understood by those skilled in this art, orientation of the fastener elements significantly reduces the feed rate of the female fastener elements to the installation head and requires special orientation equipment.
The panel to which the female fastener element is attached may be simultaneously formed by the die press during each stroke of the die press. Thus, the feed rate also affects the cycling of the die press during forming of the panel. In a typical application, the panel is attached to another component of the assembly by a bolt, screw or other male threaded fastener which is received in the bore of the self-attaching female fastener element. It is, therefore, advantageous that the female fastener element form a flush mounting with the panel to avoid the requirement for embossing the panel or providing a spacer when attaching a component to the panel. As will be understood by those skilled in this art, a flush mounted self-attaching female fastener element does not project beyond one plane of the panel following attachment.
The self-attaching female fastener element and method of installation of this invention avoids the problems associated with the prior art and may be formed by conventional cold forming techniques, including cold heading or progressive die techniques.